- ID:
- ivo://CDS.VizieR/J/other/Sci/340.170
- Title:
- Classifications of 188 SNe Ia
- Short Name:
- J/other/Sci/340.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Type Ia supernovae (SNe Ia) have been used as excellent standardizable candles for measuring cosmic expansion, but their progenitors are still elusive. Here, we report that the spectral diversity of SNe Ia is tied to their birthplace environments. We found that those with high-velocity ejecta are substantially more concentrated in the inner and brighter regions of their host galaxies than are normal-velocity SNe Ia. Furthermore, the former tend to inhabit larger and more luminous hosts. These results suggest that high-velocity SNe Ia likely originate from relatively younger and more metal-rich progenitors than do normal-velocity SNe Ia and are restricted to galaxies with substantial chemical evolution.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/PASP/115/1280
- Title:
- Classifications of SN host galaxies
- Short Name:
- J/PASP/115/1280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Classifications on the DDO system are given for an additional 231 host galaxies of supernovae that have been discovered during the course of the Lick Observatory Supernova Search with the Katzman Automatic Imaging Telescope (KAIT). This brings the total number of hosts of supernovae (SNe) discovered (or independently rediscovered) by KAIT, which have so far been classified on a homogeneous system, to 408.
- ID:
- ivo://CDS.VizieR/J/PASP/117/773
- Title:
- Classifications of SN host galaxies. III
- Short Name:
- J/PASP/117/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A homogeneous sample comprising host galaxies of 604 recent supernovae, including 212 objects discovered primarily in 2003 and 2004, has been classified on the David Dunlap Observatory system.
- ID:
- ivo://CDS.VizieR/J/AJ/141/189
- Title:
- Classifiers for star/galaxy separation
- Short Name:
- J/AJ/141/189
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the star/galaxy classification efficiency of 13 different decision tree algorithms applied to photometric objects in the Sloan Digital Sky Survey Data Release Seven (SDSS-DR7). Each algorithm is defined by a set of parameters which, when varied, produce different final classification trees. We extensively explore the parameter space of each algorithm, using the set of 884,126 SDSS objects with spectroscopic data as the training set. The efficiency of star-galaxy separation is measured using the completeness function.
- ID:
- ivo://CDS.VizieR/J/MNRAS/470/1291
- Title:
- Classifying 3FGL with ANN
- Short Name:
- J/MNRAS/470/1291
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In its first four years of operation, the Fermi-Large Area Telescope (LAT) detected 3033 {gamma}-ray emitting sources. In the Fermi-LAT Third Source Catalogue (3FGL) about 50 per cent of the sources have no clear association with a likely {gamma}-ray emitter. We use an artificial neural network algorithm aimed at distinguishing BL Lacs from FSRQs to investigate the source subclass of 559 3FGL unassociated sources characterized by {gamma}-ray properties very similar to those of active galactic nuclei. Based on our method, we can classify 271 objects as BL Lac candidates, 185 as FSRQ candidates, leaving only 103 without a clear classification. We suggest a new zoo for {gamma}-ray objects, where the percentage of sources of uncertain type drops from 52 per cent to less than 10 per cent. The result of this study opens up new considerations on the population of the {gamma}-ray sky, and it will facilitate the planning of significant samples for rigorous analyses and multiwavelength observational campaigns.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/4416
- Title:
- Classifying galaxy spectra at 0.5<z<1
- Short Name:
- J/MNRAS/478/4416
- Date:
- 10 Dec 2021 13:08:01
- Publisher:
- CDS
- Description:
- The spectrum of a galaxy contains information about its physical properties. Classifying spectra using templates helps to elucidate the nature of a galaxy's energy sources. In this paper, we investigate the use of self-organizing maps in classifying galaxy spectra against templates. We trained semi-supervised self-organizing map networks using a set of templates covering the wavelength range from far ultraviolet to near-infrared. The trained networks were used to classify the spectra of a sample of 142 galaxies with 0.5<z<1 and the results compared to classifications performed using K-means clustering, a supervised neural network, and chi-squared minimization. Spectra corresponding to quiescent galaxies were more likely to be classified similarly by all methods while starburst spectra showed more variability. Compared to classification using chi-squared minimization or the supervised neural network, the galaxies classed together by the self-organizing map had more similar spectra. The class ordering provided by the 1D self-organizing maps corresponds to an ordering in physical properties, a potentially important feature for the exploration of large data sets.
- ID:
- ivo://CDS.VizieR/J/AZh/89/611
- Title:
- Class I methanol maser catalog
- Short Name:
- J/AZh/89/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have revised the Astro Space Center catalog of Class I methanol masers detected in starforming regions (MMI/SFR), mainly at 44GHz, and created a new electronic version of the catalog. Currently, the catalog contains 206 objects, selected from publications through 2011 inclusive. The data from the survey of Chen et al. (2011, Cat. J/ApJS/196/9), performed specifically for objects EGO, which form a new specific catalog, are not included. The MMI/SFR objects were identified with emission and absorption objects in the near IR, detected during the MSX and Spitzer space missions. Seventy-one percent of Class I methanol masers that emit at 44GHz and fall within the Galactic longitude range surveyed by Spitzer (GLIMPSE) are identified with Spitzer Dark Clouds (SDCs), and 42% with Extended Green Objects (EGOs). It is possible that Class I methanol masers arise in isolated, self-gravitating clumps, such as SDCs, at certain stages of their evolution. A sample of SDCs is proposed as a new target list for Class I methanol maser searches. A detailed statistical analysis was carried out, taking into account the characteristics of the regions of MMI/SFR formation presented in the catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A33
- Title:
- Class 0 sources continuum subtracted UV-tables
- Short Name:
- J/A+A/590/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The physical structure of deeply-embedded low-mass protostars (Class 0) on scales of less than 300AU is still poorly constrained. While molecular line observations demonstrate the presence of disks with Keplerian rotation toward a handful of sources, others show no hints of rotation. Determining the structure on small scales (few 100AU) is crucial for understanding the physical and chemical evolution from cores to disks. To determine the presence and characteristics of compact, disk-like structures in deeply-embedded low-mass protostars. A related goal is to investigate how the derived structure affects the determination of gas-phase molecular abundances on hot-core scales. Two models of the emission, a Gaussian disk intensity distribution and a parametrized power-law disk model, are fitted to sub-arcsecond resolution interferometric continuum observations of five Class 0 sources, including one source with a confirmed Keplerian disk. Prior to fitting the models to the de-projected real visibilities, the estimated envelope from an independent model and any companion source are subtracted. For reference, a spherically symmetric single power-law envelope is fitted to the larger scale (~1000AU) emission and investigated further for one of the sources on smaller scales.
- ID:
- ivo://CDS.VizieR/VIII/72
- Title:
- CLASS survey of radio sources
- Short Name:
- VIII/72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cosmic Lens All-Sky Survey (CLASS) is an international collaborative program aimed at obtaining high-resolution radio images of over 10000 flat-spectrum radio sources in order to create the largest and best studied statistical sample of radio-loud gravitationally lensed systems. CLASS is aimed at identifying lenses where multiple images are formed from compact flat-spectrum radio sources, which should be easily identifiable in the radio maps (Browne et al., 2003MNRAS.341...13B). In four observing ``seasons'' from 1994-1999, CLASS has observed 13832 radio sources. When combined with the JVAS survey, the CLASS sample contains over 16,000 images. Using the GB6 and NVSS surveys, a complete statistical subset of 11685 sources has been constructed. These were selected from the NVSS 20-cm (Condon et al., 1998, Cat. <VIII/65>) and GB6 6-cm (Gregory et al., 1996, Cat. <VIII/40>) catalogues by the selection criteria: declination >0deg, |b|<10deg, S(6cm)>=30mJy, and spectral index between 6 and 20cm flatter than -0.5 (S proportional to frequency^+alpha^). The remaining sources were selected using earlier versions of these catalogues or with slightly relaxed versions of these criteria.
- ID:
- ivo://CDS.VizieR/J/ApJ/830/127
- Title:
- CLASSy: CARMA obs. in L1451 region of Perseus
- Short Name:
- J/ApJ/830/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a 3mm spectral line and continuum survey of L1451 in the Perseus Molecular Cloud. These observations are from the CARMA Large Area Star Formation Survey (CLASSy), which also imaged Barnard 1, NGC1333, Serpens Main, and Serpens South. L1451 is the survey region with the lowest level of star formation activity-it contains no confirmed protostars. HCO^+^, HCN, and N_2_H^+^ (J=1->0) are all detected throughout the region, with HCO^+^ being the most spatially widespread, and molecular emission seen toward 90% of the area above N(H_2_) column densities of 1.9x10^21^cm^-2^. HCO^+^ has the broadest velocity dispersion, near 0.3km/s on average, compared with ~0.15km/s for the other molecules, thus representing a range of subsonic to supersonic gas motions. Our non-binary dendrogram analysis reveals that the dense gas traced by each molecule has a similar hierarchical structure, and that gas surrounding the candidate first hydrostatic core (FHSC), L1451-mm, and other previously detected single-dish continuum clumps has similar hierarchical structure; this suggests that different subregions of L1451 are fragmenting on the pathway to forming young stars. We determined that the three-dimensional morphology of the largest detectable dense-gas structures was relatively ellipsoidal compared with other CLASSy regions, which appeared more flattened at the largest scales. A virial analysis shows that the most centrally condensed dust structures are likely unstable against collapse. Additionally, we identify a new spherical, centrally condensed N_2_H^+^ feature that could be a new FHSC candidate. The overall results suggest that L1451 is a young region starting to form its generation of stars within turbulent, hierarchical structures.
